AUBURN HILLS, Mich. (AP) -- Joe Dumars and the Detroit Pistons had been waiting a while for this offseason - and it showed.

The Pistons have finally been able to give their roster a significant makeover, adding Josh Smith, Chauncey Billups and Italian star Luigi Datome. It remains to be seen how much the team will improve, but for the first time in a while, there's a bit of a buzz surrounding this struggling franchise.

After four straight seasons without a playoff berth, Detroit entered the offseason with plenty of space under the salary cap. Dumars, the general manager, said this week he's accomplished what he wanted to via free agency.

''The only thing left now is trade possibilities, and that door will continue to be open,'' he said.

Detroit's rebuilding process has been slow. First, Tom Gores became the team's new owner in 2011 following a drawn-out sale that added to the sense of gloom hanging over the team. Over the next couple years, the Pistons parted ways with Richard Hamilton, Ben Gordon and Tayshaun Prince, giving themselves flexibility they would put to use in 2013.

Smith is the key free agent addition. The 6-foot-9 forward joins a front line that already includes promising big men Greg Monroe and Andre Drummond.

''We spent a lot of time preparing for this offseason,'' Gores said. ''Our folks put the pieces in place to make some important moves that will make this team more competitive immediately, while at the same time nurturing our nucleus of young talent.''

Detroit hired Maurice Cheeks as its new coach in June, but when the Pistons drafted guard Kentavious Caldwell-Pope later that month, passing on local favorite Trey Burke of Michigan, it looked like they would again struggle to win back the support of an increasingly apathetic fan base.

The free agent moves have added some much-needed intrigue to the coming season.

The popular Billups was the MVP of the 2004 NBA Finals with the Pistons. He was traded four years later, and bringing him back as a free agent gives the team a veteran who may be able to help mentor young guard Brandon Knight.

''Obviously, the team and the organization have kind of struggled for a few years. It's not what it used to be when I was here, and I just want to be a part of bringing it back to respectability,'' Billups said. ''I think we've got some really good young players on the team.''

The 25-year-old Datome, meanwhile, is a bit of an unknown commodity. The 6-foot-7 forward could give Detroit some quality outside shooting if he can adjust after arriving from Europe.

''I'm curious to see how I can fit in the NBA game. For sure, it looks more athletic, more physical,'' he said. ''I know that maybe I will need some time to adapt myself and my game for the NBA game, but I know that I have veteran players who can help.''

Dumars remained open to the possibility of more changes, but the roster that starts the season may look similar to what's already been assembled. Dumars said the team didn't use its amnesty waiver on forward Charlie Villanueva because Detroit didn't need more cap space. Dumars also said Villanueva's skill set - he's a 6-foot-11 forward who made 90 shots from 3-point range last season - could still be of use to the Pistons.

''I'm really comfortable now with this roster,'' Dumars said. ''But as I was saying a little while ago, you can't shut the door now and say, 'OK, we're done.' It's the middle of July right now.''

There is still plenty of room for improvement, but as promised, the Pistons have been busy this offseason. They couldn't afford to wait any longer.

''We're on our way to fulfilling our promise to revitalize this franchise and make the Pistons competitive again,'' Gores said. ''We're not finished yet, and we still need to prove it on the floor. But I'm pleased with the moves we've made so far. Joe Dumars and the basketball operations team have put a lot of pieces in place to move this team forward.''